The present invention pertains to a bellows seal on a ball-and-socket provided with a joint ball and a ball pivot, especially on a ball-and-socket joint of a chassis bearing, with an elastic bellows, which has a pivot-side opening and a joint-side opening and surrounds the ball pivot of the ball-and-socket joint, wherein a said circumferential, elastic and outwardly pointing sealing lip, which is in contact with a sealing surface, is provided at the pivot-side opening of the sealing bellows, wherein an L-ring, whose first leg points essentially in the axial direction (axial leg) and whose second leg points radially to the outside (radial leg), is provided at the pivot-side opening.
DE 36 18 565 C2 describes a bellows seal on a ball-and-socket joint provided with joint ball and ball pivot, especially a ball-and-socket joint of a chassis bearing, with an elastic bellows, which has a pivot-side opening and a joint-side opening and surrounds the ball pivot of the ball-and-socket joint, wherein a circumferential, elastic sealing lip pointing to the outside is provided at the pivot-side opening of the sealing bellows.
A bellows seal has been known from German Auslegeschrift DE 12 66 074. This Auslegeschrift shows a bellows seal on a ball-and-socket joint provided with joint ball and ball pivot with an elastic bellows, which has a pivot-side opening and a joint-side opening and axially surrounds the ball pivot of the ball-and-socket joint, wherein a circumferential, elastic sealing lip pointing to the outside is arranged at the pivot-side opening of the sealing bellows. Furthermore, a crown-like cylinder ring, which is provided with grease discharge channels and is to bring about a stiffening of the end of the bellows, is arranged at the pivot-side opening.
It has been found during the use of such bellows seals, especially in the area of chassis bearings, that such an embodiment is susceptible to corrosion and the sealing effect of the bellows seal declines after an excessively short time of use.
The object of the present invention is therefore to provide a bellows seal that brings about better and more lasting sealing and whose susceptibility to corrosion is reduced.
According to the invention a ball-and-socket joint bellows seal is provided. The ball-and-socket joint has a joint ball and a ball pivot, especially on a ball-and-socket joint of a chassis bearing, with an elastic bellows. The elastic bellows has a pivot-side opening and a joint-side opening and surrounds the ball pivot of the ball-and-socket joint. A circumferential, elastic and outwardly pointing sealing lip is in contact with a sealing surface. The sealing lip is provided at the pivot-side opening of the sealing bellows, wherein an L-ring, whose first leg points essentially in an axial direction (axial leg) and whose second leg points radially to the outside (radial leg), is provided at the pivot-side opening. The radial leg engages a groove extending on the inside of the sealing bellows and the inner side of the axial leg is sealingly in contact with an opposite running surface.
Thus, it is proposed that a bellows seal for a ball-and-socket joint provided with joint ball and ball pivot, especially for a ball-and-socket joint of a chassis bearing, with an elastic bellows, which has a pivot-side opening and a joint-side opening and axially surrounds the ball pivot of the ball-and-socket joint, wherein a circumferential, elastic and outwardly pointing sealing lip, which can be in contact with a sealing surface, is provided at the pivot-side opening of the sealing bellows, be further improved such that an L-ring, whose first leg points essentially in the axial direction (axial leg) and whose second leg points radially to the outside (radial leg), is provided at the pivot-side opening, wherein the radial leg engages or is anchored in a groove extending on the inside of the sealing bellows and the inner side of the axial leg is sealingly in contact with an opposite surface.
It is achieved with this embodiment according to the present invention that the bellows seal has a preliminary seal and a principal seal. The preliminary seal comprises the sealing lip and the opposite sealing surface. This preliminary seal keeps out essentially coarse dirt and other coarser contaminants. The principal seal is located in the protected area and is formed by the L-ring and a running surface.
The bellows seal may be designed in an advantageous manner such that the running surface located sealingly opposite the inside of the axial leg forms part of the ball pivot, and the cylindrical part of the ball pivot is preferably used for this purpose.
In another advantageous embodiment, the sealing lip, the sealing surface, the L-ring and the ball pivot form a hollow space, which may also be filled with grease, silicones or other agents to improve the sealing.
In another, particularly advantageous embodiment of the bellows seal, an intermediate ring is pulled on the ball pivot radially inside the L-ring, so that its outside forms a running surface for the axial leg of the L-ring. It is possible as a result to obtain especially favorable sliding properties and sealing properties between the L-ring and the intermediate ring by correspondingly selecting the materials of the L-ring and the intermediate ring. Furthermore, corrosion of the sealing seat is prevented by the intermediate ring. The intermediate ring may advantageously have a U-shaped design, wherein the outer legs or the outer beads point radially to the outside and a running surface is thus formed between the two beads, in which the L-ring is arranged in its position in a well-defined manner.
To simplify assembly, the intermediate ring may also be divided in the circumferential direction, so that the U-ring is composed of two mutually opposite L-shaped rings of identical design.
In another, particularly advantageous embodiment of the bellows seal, the length of the radial leg of the L-ring and the depth of the groove, which is engaged by the radial leg, are coordinated with one another such that a distance a is formed between the outside of the axial leg of the L-ring and the bellows. The sealing bellows has additional freedom of movement and elasticity due to this design, which leads to a longer service life of the sealing bellows.
The bellows seal may be advantageously also designed such that the L-ring is so elastic that the angle between the axial leg and the radial leg of the L-ring can be changed during the assembly. This means that the L-ring is stressed during the assembly, and this stress improves the seating of the L-ring on the running surface. Premature release or slipping off of the L-ring from the running surface is thus prevented from occurring.
Furthermore, the L-ring and/or the intermediate ring may be made of plastic. Graphite-reinforced PTFE has proved to be particularly advantageous.
Consequently, an especially advantageous embodiment of the design has an L-shaped sealing ring made of plastic, which exerts a shape-stabilizing effect for the pivot-side sealing seat at the same time. Graphite-reinforced PTFE, which has proved to be advantageous in sealing systems and has higher wear resistance and elasticity than pure PIFE, may be used as the material for the L-ring. The widening of the L-ring during assembly leads to increased surface pressure, which prevents water from penetrating. For simplified assembly, the pivot of the ball-and-socket joint has a bead, on which the L-ring can be supported.
This mode of construction separates the keeping away of dirt and splash water from the sealing against seeping water and other moisture. It is advantageous for optimal function to coat the sealing surface located opposite the sealing lip of the sealing bellows in order not to increase the wear on the sealing surfaces by rust particles. Another possibility is to use a corrosion-protected washer as a sealing surface.
The features of the present invention, which were described above and will be explained below, may be used, of course, not only in the particular combination described, but also in other combinations or alone without going beyond the scope of the present invention.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.